Did you manage it? Here's a version that works.

decision = input("Do you want to enter? [Y,N]: ")
if decision == "N" or decision == "n":
    print("Your quest is at an end, goodbye!")
elif decision == "Y" or decision == "y":
    print("You enter the mines.")
    print("The way is lit by candles on the wall.")
else:
    print("A hole opens up below you, and you plunge into darkness. Goodbye!")



So, we have one decision in our game! We need one more piece of information, and we'll be able to build a full interactive story...